Reaction Wheel Assemblies (RWA) are commonly deployed onboard satellites and other vehicles for attitude adjustment purposes. By common design, a RWA contains a rotor having a rotor shaft fixedly joined to an inertial element, such as an outer ring or rim. The rotor is typically mounted within a housing assembly including upper and lower halves, which are sealingly joined to enclose the rotor. The opposing ends of the rotor shaft are received within cylindrical cavities or bores provided in the housing assembly. Spin bearings are positioned around the shaft ends to facilitate rotation of the rotor relative to the housing assembly. During operation of the reaction wheel, a spin motor drives rotation of the rotor about a spin axis at a relatively high rate of speed thus establishing momentum. When it is desired to adjust the attitude of the host vehicle, control circuitry commands the spin motor to alter the rotational speed of the rotor and thereby change the momentum. The momentum change and resulting RWA system output torque is transferred, through the RWA housing assembly, and to the host vehicle to effectuate the desired attitude adjustment.
A single RWA can be combined with additional RWAs to produce a Reaction Wheel Assembly Array (RWAA). An RWAA containing at least three RWAs can perform highly controlled attitude adjustments about all three orthogonal axes. RWAA performance is optimized when the RWAs are mounted to the host vehicle such that a precise spatial relationship is achieved between the spin axes of the RWAs; e.g., when the RWAA contains three RWAs, the spin axes are ideally positioned in an exact orthogonal relationship. During installation of the RWAA, each RWA may be individually bolted or otherwise affixed to a different mounting interface provided on the host vehicle. In many cases, it may be necessary to adjust the orientation of each RWA to ensure that its spin axis is accurately oriented with respect to the spin axes of the other, separately-mounted RWAs. This wheel mounting process is typically carried-out by the customer or purchaser of the RWAs (as opposed to the RWA manufacturer) and can be undesirably timely, cumbersome, and complex to perform.
It is thus desirable to provide a Reaction Wheel Assembly Array wherein proper positioning between the spin axes of the RWAs (or rotor assemblies) included within the RWAA is achieved, while the above-described RWA mounting process is avoided. It would be particularly desirable if the positioning of the spin axes could be fixed or predetermined by the RWAA manufacturer in a highly precise, reliable, and straightforward manner. Ideally, embodiments of such an RWAA would also have a reduced part count, complexity, size, weight, and/or cost of manufacture as compared to conventional RWAAs. Still further desirable features of such an RWAA may include a centralized electronic infrastructure, improved radiation shielding provided by infrastructure outboard of the electronics, simplified evacuation port plumbing, and/or an overall increase in the structural robustness of the RWAA. Other desirable features and characteristics of embodiments of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying drawings and the foregoing Background.
The above-described limitations associated with conventional RWAAs are provided to establish an exemplary context in which embodiments of the present invention may be better understood and without implicit admission that any such limitations or drawbacks have been recognized by others in the relevant field. Similarly, the statements contained in the foregoing Background shall not, under any circumstances, be construed as an implicit admission that others in the relevant filed have recognized the desirability of producing an RWAA having the features or characteristics identified above as desirable, beneficial, or advantageous.